Cards are widely exchanged and used as a medium to transfer or communicate some messages between users because of their convenience, limited space occupation, and easiness to keep with. They are specially useful in nowaday commercial society. However, when used in a large scale show, exhibition, or other similar activities, they are usually distributed or exchanged at a lot of increased labors, time, and costs while a desired effect is not necessarily achieved and a large part of distributed cards might very possibly be wasted.
It is therefore tried by the applicant to develop an unattended card exchange unit which can be used in a show or exhibition stand to automatic exchange cards with any visitor when no one attends the exhibition floor.